On the Entropy of Music: An Experiment with Bach Chorale Melodies

The information content, or ‘entropy, of a piece of music cannot be determined in the abstract, but depends on the listener’s familiarity with, and knowledge of, the genre to which it belongs. This paper describes an ongoing experiment designed to investigate human listeners’ models of music by having them guess successive notes in a piece. The first part of the experiment was administered by a computer program, and in order to elicit subjective probabilities, listeners gambled on their guesses. The study was restricted to the music of the Bach Chorales and, in particular, to the succession of pitches that comprise the melody—although this methodology is also generally applicable to other musical parameters and to other genres.